PROJECT SUMMARY The long-term goal of this project is to determine the metabolic regulation of NK cell effector functions to improve our understanding of basic mechanisms of NK cell activation in health and disease. Natural killer (NK) cells are innate immune lymphocytes that serve as a critical first line defense against infection, particularly viruses, and are important for tumor immunosurveillance. NK cells mediate their effects via two mechanisms: production of cytokines (especially IFN-gamma) and target cell killing. NK cell effector functions can be triggered by inflammatory cytokines or engagement of germline-encoded activating receptors whose ligands are displayed by infected and/or tumor cells. Metabolic regulation plays a key role in many aspects of immunity, including the activation and generation of memory T cells. There are two primary metabolic pathways for generating intracellular energy (ATP), glycolysis and mitochondrial oxidative phosphorylation (OXPHOS). The fuels that drive cellular metabolism (e.g., glucose, fatty acids) are altered in many disease states, and metabolic pathways are promising targets for drug candidates. While triggers of NK cell activation and subsequent NK cell effector responses have been well-characterized, the metabolic fuels required for NK cell functional responses, and the concept of metabolic regulation of NK cell activation are largely unexplored. Our preliminary data demonstrates that both OXPHOS and glycolysis are required for activation of NK cells by activating receptors, but that cytokine stimulation of NK cells does not require a specific metabolic pathway. Following priming with IL-15, the metabolic requirements for NK cell activation are altered, and NK cells have preserved function in response to receptor activation with metabolic inhibition. This proposal presents a 5 year plan to investigate the metabolic regulation of NK cell activation. We hypothesize that alterations of intrinsic cellular metabolism will impact NK cell function in vivo. The specific aims of this proposal are to investigate: 1) the mechanisms by which receptor stimulation of NK cells is dependent on metabolism and how IL-15 priming alters this, and 2) the metabolic requirements for NK cell differentiation and response to viral infection in vivo using genetically targeted mouse models. These studies will provide insight into metabolic pathways that control NK cell activation, and potential pathways to target in patients to enhance NK cell function.